FWIW I've seen tps do this on some high mileage cars (not ls) but gm - no code ,intermittent high idle speed. Hard to diagnose, lots of on road time with live data displayed

 

If they charged you for TPS, make sure to get the old part. FYI - Need a scope to best see if a tps is working without any kind of flaky spot while sweeping from 0 to 100% throttle.

 

So yesterday it drove fine, no auto pilot on the street, ran fine on the highway. Today I cranked it cold start and it idles fine, but as soon as I put it into reverse it chugged and stalled. Did it again, same result. Tried again after leaving it idling for a few minutes, same result. Had to keep my left foot on the brake and right foot keeping the RPM's at 1 grand while shifting into reverse and keeping my foot barely applied to the fuel while reversing to keep it running. Put it in drive, stall...same technique and it goes in Drive and was able to drive it. It didnt stall at stop lights but as soon as I put it in park and re-shift into drive or reverse? Stall.

It doesnt seem like its misfiring or lacking in power when driving it, however still no kickback into 2nd or 3rd at WOT at 50 MPH + ... The stall flashes to 3 grand but it puts it back into 4th.

Oh and I got a MIL after I was done testing it... getting that scanned as we speak.

 

TPS seemed unlikely as the root cause of the issue lol. Hopefully the MIL points to something that they can fix, otherwise its back to being a tune issue.

 

seems TPS is still faulting.

I called the shop and they said it may be old codes that need to be deleted by a real scanner and not HPTuners.

I'm really not trusting this shop much anymore. I'm thinking they're just trying to get by or they know something that they're refusing to tell me. I'm thinking of going up to LSX Powertuning and letting them have a look at this.

Edit: Can anything in the tune affect TPS readings enough to cause a MIL? Also what about the Throttle Body? I did upgrade it to a 92MM

 

BS.....HPT can not only clear a code but delete the TPS code from ever turning on. You need tuning with a new/bigger throttle body. I'd give them 1 more shot, otherwise ask for your money back and go elsewhere. @LSX Power Tuning has a good rep.

 

The shop that did this was SWG Performance in Temple TX. Looking at their work they should seem smart enough to know what the deal is and it really feels like they know it has issues but refusing to tell me for some reason. Temple is about 50 miles away from here. Unfortunately all the good shops in Austin area are full through Spring.

I could just go to LSX Powertuning and dispute the cost of the tune on my credit card, I dont think I'm going to get much in the way of getting my money back without going above them as they will probably just give me more excuses.

 

That's your call. Glad you paid with your CC, that was smart!

 

Yeah I normally hate using CC's but I've been burnt by shops before so I used it to take precautions. They also never dyno-tuned it, they just used HPTuners. They wanted me to put 1k miles on it to break it in first but when I was ready to pick it up they seemed very hesitant about releasing it, kinda like they weren't really ready, which is why I'm very leery about whats going on.

Anyway this is what the owner texted back:



I'm probably just going to eat it and go to LSX Powertuning tomorrow. I really need to know whats going on here. If they manage to fix it I'll just dispute the costs, if not then I'll eat the $650.

 

That info about 1000 mile break-in and those texts are sketchy.....

 

What I'm really worried about is they didn't tune it at all, that or they purposefully f*d it up knowingly, hoping I would drive it and destroy it to yank more money out of me since I brought my own motor. I'm unsure what their intentions are or why they released it like this but if you saw their shop in person, as well as the other cars they've been working on you would never believe they would release a car running the way mine is... They had several LS pickups and a vet, all of them seemingly running perfectly. I paid them a fair penny to do this job but they may have had more expensive projects in the pipe and shafted mine for bigger dollar priorities... I'm unsure... but I know this is far from their best work.

 

If you haven't id do an oil change immediately and throw some fuel injector cleaner in it. Make sure it's not low on oil and try to help anything in the fuel system that's dirty.

 

I feel your pain from years ago. We trailered my LT1 over a hr to have my car dyno tuned at a shop that like your place had nice cars. Owner had a mustang he built and was done up. I already had a Ed Wright mail order tune so car ran pretty good. Had some mild work and a Vortech blower. They had my car for a whole day. Called them to see how it was going and couldn’t get a straight answer so we drove up there. They said it’s going to cost you $1,000.00 but we couldn’t tune your car or get it running right... Ah it ran fine before it came here. We spent hrs on the dyno and can’t figure it out. We take a drive around the parking lot with tuner driving and he says see it wants to stall when you floor it. So since I signed a waiver and didn’t know any better about fighting the charge on my CC ages ago I had to pay it. He basically said pay or your car stays here till you do. Drive a mile down the street and the car sputters and shuts down at 70mph. Call the shop and owner finally answers and tell him car is dead and won’t turn over. He goes what do you want me to do about it we are closed and going home. I said come get me and my car. He said we are closed can’t help you. I know what I wanted to do that’s for sure!!

 

I probably would have paid but not signed the waiver and would have disputed the CC charge after getting my car back, I'd have had a cop down there and a tow truck ready to pick up my car if they pulled some **** like that on me. But no, I'm not going back there tomorrow. I think what it is, they really just don't care how the car turns out.

 

So I tried to crank it to put it in the garage tonight. It cranks, idles very unstable at first...smoothens out alittle bit but put it in gear and it dies. Its seemingly not liking cooler weather. It seemed to get better earlier today as the outside air got warmer. I'm unsure though.

Could anything cause the car to fry a brand new TPS sensor so quickly? or is it likely just not tuned properly and can the tune affect TPS readings?

All the symptoms seem like it really may be a bad TPS but Im clueless as it how it could have went bad so quickly.

Edit: I was looking at other threads -- This looks like it very well may be the TPS sensor:
https://ls1tech.com/forums/generatio...essing-up.html
I was having the exact same issues.

Edit 2: I'm disconnecting the battery overnight to reset the PCM and clear the codes. Will see what turns of this tomorrow.

 

I was young then and didn’t know any better and I signed the waiver as soon as I dropped the car off it was policy which I didn’t know. So once I get mine built that is my biggest worry..

 

It's stories like this that made me buy hp tuners and do it myself ( this was before the holley terminator ) it cost more than my engine. Hope you get it sorted out

 

There's literally a single table for desired idle airflow that is temperature dependent that makes all the difference in the world for idling a cammed car, especially from a cold start.

 

All this TPS is bullshit, any idiot with a half decent scantool can view live data to see if the TPS is reading correctly and consistently, and even a cheap *** tool will clear the codes.

 

This morning even after clearing the codes it wouldn't stay running until it warmed up.

I took it to LSX Powertuning.

Summary:
- Gas pedal fully depressed and it's only seeing 75% throttle. It does see 100% if you manually move the throttle body. Throttle cable has been extended too far out but we didn't adjust yet in fear of breaking the adjuster. I'm completely unsure how this shop didn't catch this.
- TPS sensor voltage is abnormally low.. he says its probably the throttle body and he can correct in the tune and TB adjustments.
- Running on mostly factory tune with the exception of advanced timing. Even trans tuning is stock.

They basically did just enough tuning so it would crank and drive out the shop

I need a new throttle cable as adjusting my current one while tuning may break it leaving me stranded.

I could make the shop adjust it but I just dont trust them anymore.